The FLIP-FIGNL1 Complex Regulates The Dissociation Of RAD51 To Maintain Genome Stability

Genome stability is a feature of every organism to preserve and faithfully transmit the genetic material from generation to generation or from one somatic cell to another.The primary causes of genomic instability are DNA damage and replication stress.Therefore,timely and efficient repair of DNA damage,as well as accurate and complete DNA replication,are crucial in maintaining genome stability and ensuring normal development at both the cellular and individual level.RAD51 is one of the most important recombinases in mammals and plays a critical role in DNA damage repair and replication stress response,thus crucial for maintaining genome stability.In homologous recombination repair,RAD51 mediates strand invasion,promoting the exchange and recombination between homologous chromatids.,thereby preserving genome integrity.RAD51 also have essential function at replication forks.During replication stress,RAD51 facilitates the reversal of stalled replication forks,protects nascent DNA,and ensures the continuity of DNA replication.Dysfunction of RAD51 severely affects genome stability,leading to lethal consequences.Cells with RAD51 expression defects are unable to survive,while various tumor cells exhibit high levels of RAD51 expression.Consequently,elucidating the function of RAD51 and its associated regulatory mechanisms is of great significance for a comprehensive understanding of tumor initiation and progression mechanisms,as well as guiding personalized therapeutic strategies and prevention of genetic diseases.Fidgetin-like protein 1(FIGNL1)has been identified as a protein that interacts with RAD51 and is involved in regulating the removal of RAD51 during homologous recombination.However,the specific regulatory mechanisms of FIGNL1 on RAD51,as well as whether it has other functions,are currently unknown.In this study,we focus on conducting in-depth research on the specific functions of FIGNL1.Through affinity purification-mass spectrometry,we discovered FLIP,also known as C1orf112,interacts with FIGNL1.Through sequence conservation analysis,protein interaction structure simulation,and coimmunoprecipitation,we found that FLIP directly interacts with the N-terminal 1-120 aa of FIGNL1 through its highly conserved WCF motif,forming a tightly interconnected complex.Knockout or knockdown of FLIP decreases the protein level of FIGNL1,and vice versa.Furthermore,we investigated the functions of FLIP-FIGNL1 and found that the complex formed by FLIP and FIGNL regulates the dissociation of RAD51 from DNA in multiple pathways,including homologous recombination and replication stress response.The absence of the FLIP-FIGNL1 complex not only leads to defects in homologous recombination but also affects the restart of replication forks,thereby impacting genome stability.Finally,we analyzed the correlation between the expression of FLIP and FIGNL1 and clinical features based on the TCGA database.Through transcriptome data analysis,we found a strong positive correlation between the expression levels of FLIP,RAD51 and FIGNL1.Moreover,the m RNA expression levels of both FLIP and FIGNL1 were significantly elevated in various tumor tissues,such as CESC,COAD,PAAD and STAD.By analyzing the overall survival period of cancer patients,we observed a significant association with FLIP/FIGNL1 expression and poor prognosis in a variety of tumor types.In summary,we have identified FLIP as a protein that interacts with FIGNL1 in human cells.The interaction between FLIP and FIGNL1 forms a complex that stabilizes each other and regulates the timely dissociation of RAD51.This complex plays a critical role in preserving the normal functions of RAD51 in essential pathways like homologous recombination and replication stress response.Our study has provided a detailed understanding of the regulatory mechanisms of FIGNL1 on RAD51 and offers a new molecular target for personalized cancer treatment and drug design.